Saturday, July 15, 2017

Tree of the Week: American Beech (Fagus grandifolia)

The American beech (Fagus grandifolia) is our shade tree of the week. The two American beeches in the arboretum collection were donated by Jack Price and planted in September 1988. They provide ample shade for the gravel pathway that runs along the brick wall near Hamilton Hall. This is a particularly shady spot of the arboretum, as there are several massive on-site natives trees. The photos below were taken shortly after noon on a partly cloudy day.

The gravel pathway running parallel to the brick wall is shaded by two American beeches (Fagus grandifolia). A very large loblolly pine (Pinus taeda) separates the beeches, with a water oak (Quercus nigra) in the background, closer to the wall.The photos below are of the beech on the right side of the photograph.
The two American beeches in the collection are planted at the top of a slope. The noon sun is lighting up the grass on the opposite side of the gravel path.
Fagus grandifolia provides dense shade, making it difficult for anything to grow underneath it.
The dark green foliage of Fagus grandifolia.
An abandoned exoskeleton clings to a twig of the Fagus grandifolia. The underside of the leaves shows a characteristic vein pattern.
Not much light shines through the dense leaf layers.
The thin papery bark seems to show every little nick or scrape.
Shallow roots of Fagus grandifolia make it difficult to mow, but luckily not much grows to necessitate mowing.

You can find more pictures of the arboretum's American beeches here.

For more information about this species consult the following:
Louisiana Plant Identification and Interactive Virtual Tours (LSU AgCenter)
University of Kentucky College of Agriculture, Food and Environment 
United States Department of Agriculture

Saturday, July 8, 2017

Tree of the Week: Persimmon (Diospyros virginiana)

Our shade tree of the week is the persimmon (Diospyros virginiana). Enough can't be said about the pair of persimmons in the arboretum collection. They are doing outstanding work, providing much needed shade along one of the main sidewalks running parallel to Hamilton Hall. They provide habitat for birds and other interesting creatures. And this time of the year the female of the species is developing fruits to be appreciated in autumn.

Persimmons do very well in northern Louisiana. The two individuals in the arboretum were both collected from the wild. Jim Robbins collected the male tree from Cypress Lake in Bossier Parish, and it was planted in the ground in the spring of 1985. Ed Leuck collected the female tree from DeSoto Parish, at a lignite mine, and planted it in the spring of 1987. Today, the two trees appear to be in competition with each other over sunlight, with the male tree winning. The male tree is noticeably larger, and more erect, while the female leans out from under the shade of the male tree.

At noon, the pair of persimmons help to shade this long stretch of sidewalk.
The male persimmon (right) is older, bigger, and stands straight-up like the lamp post. The female (left) leans away from the male tree, toward the sun.
Persimmons have dark green leaves.
Underside of persimmon leaves: foliage blocking the sun
In July, the persimmon fruits aren't even close to being ripe. Do NOT try to eat these fruits! It would be unpleasant. Click here for a picture of ripening fruits. It's best to wait until the fruit wrinkles.
The male and female trees working in concert to block the sun.
It's summer time. The insects are loud and doing interesting things.
The newly emerged cicada clings to its old exoskeleton, which is stuck to the bark of the persimmon trunk.
Mature persimmons have heavily fissured, blocky bark.


For more pictures of the arboretum's persimmon trees click here.

For more information about this species consult the following:
Louisiana Plant Identification and Interactive Virtual Tours (LSU AgCenter)
University of Kentucky College of Agriculture, Food and Environment
United States Department of Agriculture

Friday, June 30, 2017

Tree of the Week: Southern Sugar Maple (Acer barbatum)

Our shade tree of the week is the southern sugar maple (Acer barbatum), widely reported to be an "excellent" or "wonderful" shade tree. This is a medium sized tree; it grows large enough to shade a big area, but not so big that it becomes a hazard. And it delivers another service: after laboring all summer to provide us with relief from the sun, we are rewarded in the fall with showy, yellow foliage.

Southern sugar maples do well in the Centenary Arboretum. There are four individuals in the collection and they are all healthy, mature specimens. The pictures below are of an individual tree planted near the Student Union Building. The specimen was collected in 1994, from Walter Jacobs Nature Park, and subsequently planted in January 1996, making this tree well over 20 years old.

This individual southern sugar maple (Acer barbatum) is planted along the sidewalk going towards the Student Union Building. The grass under the tree is nicely shaded while the concrete sidewalk is brightly lit-up by the noon-day sun. The photo above shows the shadow of the tree creeping onto the sidewalk, and hopefully in the next several years the sidewalk will receive more coverage.
Although the concrete sidewalk is currently exposed to full noon-day sun, the gravel path is shaded by the Acer barbatum.
We have full-shade under the tree and full-sun on the other side.
Leaves of Acer barbatum are characteristically lobed.
Leaves are dark green in the summer, and we can expect them to turn yellow in the fall.
Looking up, Acer barbatum blocks the sun.
Trunk of mature tree, more than two decades old.

You can find more pictures of the arboretum's southern sugar maples here.

For more information about this species consult the following:
Stephen F. Austin State University 
NC State University
USDA Forest Service 

Friday, June 23, 2017

Tree of the Week: Redbud (Cercis canadensis)

It is now officially summer. Time to look for a spot of shade. For the next several weeks we will be looking at the arboretum's shade trees.

The redbud (Cercis canadensis) is a small shade tree. The long, slender limbs of the redbud stretch outward from the trunk, allowing the handsome heart-shaped leaves to block a good bit of the sun. Since the redbud stays small, it's a good tree to plant around buildings; you needn't worry about it getting too big and potentially hazardous. In the wild, redbuds occur as understory trees. As a result, they're shade tolerant and don't need full sun to thrive.

Due to their prolific seed production, redbuds spring up all over the arboretum. Ten individual trees of this species have been part of the arboretum collection. Currently we have eight and all have been volunteers. Since these trees started growing without authorization, it is impossible to say how old they are. The pictures below are from a tree that is at least a decade old, probably older.
This redbud tree (Cercis canadensis) grows along a major thoroughfare in the arboretum, providing good afternoon shade during summer time.
Mickle Hall stands to the east of this tree.

The redbud tree has slender branches and big leaves, blocking plenty of light.
Twigs and branchlet: underside of the heart-shaped leaves
The leaves of the redbud are a dark green in the summer.
The leguminous fruits of Cercis canadensis remain on the tree, maturing throughout the summer. They block additional sun.
Bark detail of mature Cercis canadensis

Flowers of the arboretum's redbuds can be seen here.

For more information about this species consult the following:
United States Department of Agriculture
Louisiana Plant Identification and Interactive Virtual Tours (LSU AgCenter)
University of Kentucky College of Agriculture, Food and Environment

Friday, June 16, 2017

Tree of the Week: Ironwood (Carpinus caroliniana))

Last week we took a look at the eastern hop hornbeam (Ostrya virginiana), a member of the family Betulaceae, the birch family. This week, we are "keeping it in the family," with a profile of the ironwood tree, Carpinus caroliniana, another member of BetulaceaeThe arboretum collection has a mature specimen of both birches, planted right close to each other. The ironwood is in the floodway down a bit from the eastern hop hornbeam, which is a little up the slope. Both trees are about the same size. Right now (mid-June), each is ornamented with dangling fruit clusters hidden by doubly serrate leaves. A glimpse at the bark is the quickest way to tell the two apart: the hop hornbeam looks like a wildcat climbed the trunk, shredding the bark, while the ironwood has smooth bark that appears to be covering rippling muscles.

This Carpinus caroliniana was collected from Walter Jacobs Nature Park in the spring of 1994 and planted in this bed of Louisiana irises in November 1995. This location of the arboretum can be soggy for a week at a time, whenever the campus gets a heavy rain. 
The fruit of Carpinus caroliniana is a nutlet that is concealed by leaf-like bracts. These nutlets, hidden by their bracts, dangle in inconspicuous clusters.
Branchlet ornamented with dangling fruit clusters
The doubly-serrate leaves are the same color as the light-green bracts.
The nutlets occur in pairs, and each nutlet develops out of a 3-lobed leafy bract.
Ostrya virginiana (left) and Carpinus caroliniana (right) have similar leaves and fruit clusters. 
Carpinus caroliniana is known for its muscular trunk: the grey bark appears to conceal a sinewy musculature.
The smooth bark of Carpinus caroliniana is distinct from the shredded bark of Ostrya virginiana.
Detail of smooth grey bark of Carpinus caroliniana

You can see more images of the arboretum's collection of ironwood trees here.

For more information about this species consult the following:
United States Department of Agriculture
Louisiana Plant Identification and Interactive Virtual Tours (LSU AgCenter)
University of Florida IFAS Extension 

Friday, June 9, 2017

Tree of the Week: Eastern Hop Hornbeam (Ostrya virginiana)

This week we are taking a look at Ostrya virginiana. Now is the right time of year to see why it's called the hop hornbeam tree. The "hop" comes from the tree's papery fruit coverings, which resemble hops, a critical ingredient used in the production of beer. Right now the hop hornbeam fruit clusters are greenish-white. Look closely or you might miss them; they blend in with the foliage.

This specimen of Ostrya virginiana was initially collected from Walter Jacobs Nature Park in 1994. It went in the ground in the fall of 1997.
This tree grows in the middle of a slope, above the floodway. A very old Pinus taeda, covered in  vines,  grows a little bit further down the slope (pictured above on the left).

The fruit cluster of Ostrya virginiana resembles hops. Each papery husk encloses a nutlet. 
The fruit clusters are abundant, but their greenish-white color makes it easy to overlook them.
Branch with leaves and fruits.
The leaves of Ostrya virginiana are finely-toothed.
Another look at the serrated leaves.
The outermost layer of this Ostrya virginiana's bark is grey colored with a shredded texture.
Beneath that the color is rusty brown.

You can see more images of the arboretum's eastern hop hornbeams here.

For more information about this species consult the following:
United States Department of Agriculture
Louisiana Plant Identification and Interactive Virtual Tours (LSU AgCenter)
University of Kentucky College of Agriculture, Food and Environment


Thursday, June 1, 2017

What's in Bloom?

Elderberry (Sambucus canadensis) grows wild in the wet areas of the arboretum. It will take over if we let it.
There is a thick patch of golden canna (Canna flaccida) growing next to the long white wooden bridge.
Basswood (Tilia caroliniana) flowers aren't showy, but have a nice fragrance.
This yellow pom-pom is from a small golden St. John's wort (Hypericum frondosum) bush.
French mulberry (Callicarpa americana) bushes are found all over the arboretum. These bushes are more noticeable in autumn when they have the bright purple berries.
Magnolia grandiflora is still in bloom! This is from the tree located near the Fitness Center.